Re: [PATCH 3/4] xfs/016: calculate minimum log size and end locations

[Allison Collins <allison.henderson@xxxxxxxxxx>]

On 6/21/19 2:18 AM, Eryu Guan wrote:
> On Tue, Jun 18, 2019 at 02:07:21PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
> >
> > xfs/016 looks for corruption in the log when the log wraps.  However,
> > it hardcodes the minimum log size and the "95%" point where it wants to
> > start the "nudge and check for corruption" part of the test.  New
> > features require larger logs, which causes the test to fail when it
> > can't mkfs with the smaller log size and when that 95% point doesn't put
> > us within 20x "_log_traffic 2"s of the end of the log.
> >
> > Fix the first problem by using the new min log size helper and replace
> > the 95% figure with an estimate of where we need to be to guarantee that
> > the 20x loop wraps the log.
> >
> > Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> Call for reviews from other XFS folks :)
>
> Thanks!
>
> Eryu
>
> > ---
> >   tests/xfs/016     |   50 ++++++++++++++++++++++++++++++++++++++------------
> >   tests/xfs/016.out |    1 +
> >   2 files changed, 39 insertions(+), 12 deletions(-)
> >
> >
> > diff --git a/tests/xfs/016 b/tests/xfs/016
> > index 3407a4b1..aed37dca 100755
> > --- a/tests/xfs/016
> > +++ b/tests/xfs/016
> > @@ -44,10 +44,21 @@ _block_filter()
> >   
> >   _init()
> >   {
> > +    echo "*** determine log size"
> > +    local sz_mb=50
> > +    local dsize="-d size=${sz_mb}m"
> > +    local lsize="-l size=$(_scratch_find_xfs_min_logblocks $dsize)b"
> > +    local force_opts="$dsize $lsize"
> > +    _scratch_mkfs_xfs $force_opts >> $seqres.full 2>&1
> > +
> > +    # set log_size and log_size_bb globally
> > +    log_size_bb=`_log_size`
> > +    log_size=$((log_size_bb * 512))
> > +    echo "log_size_bb = $log_size_bb log_size = $log_size" >> $seqres.full
> > +
> >       echo "*** reset partition"
> > -    $here/src/devzero -b 2048 -n 50 -v 198 $SCRATCH_DEV
> > +    $here/src/devzero -b 2048 -n $sz_mb -v 198 $SCRATCH_DEV # write 0xc6
> >       echo "*** mkfs"
> > -    force_opts="-dsize=50m -lsize=$log_size"
> >       #
> >       # Do not discard blocks as we check for patterns in free space.
> >       #
> > @@ -65,6 +76,9 @@ _init()
> >       . $tmp.mkfs
> >       [ $logsunit -ne 0 ] && \
> >           _notrun "Cannot run this test using log MKFS_OPTIONS specified"
> > +
> > +    # quotas generate extra log traffic so force it off
> > +    _qmount_option noquota
> >   }
> >   
> >   _log_traffic()
> > @@ -157,6 +171,7 @@ _check_corrupt()
> >   # get standard environment, filters and checks
> >   . ./common/rc
> >   . ./common/filter
> > +. ./common/quota
> >   
> >   # real QA test starts here
> >   _supported_fs xfs
> > @@ -164,10 +179,6 @@ _supported_os Linux
> >   
> >   rm -f $seqres.full
> >   
> > -# mkfs sizes
> > -log_size=3493888
> > -log_size_bb=`expr $log_size / 512`
> > -
> >   _require_scratch
> >   _init
> >   
> > @@ -188,18 +199,29 @@ echo "log sunit = $lsunit"			>>$seqres.full
> >   [ $head -eq 2 -o $head -eq $((lsunit/512)) ] || \
> >       _fail "!!! unexpected initial log position $head vs. $((lsunit/512))"
> >   
> > -# find how how many blocks per op for 100 ops
> > +# find how how many blocks per op for 200 ops
> >   # ignore the fact that it will also include an unmount record etc...
> >   # this should be small overall
> >   echo "    lots of traffic for sampling" >>$seqres.full
> > -sample_size_ops=100
> > +sample_size_ops=200
> >   _log_traffic $sample_size_ops
> >   head1=`_log_head`
> >   num_blocks=`expr $head1 - $head`
> >   blocks_per_op=`echo "scale=3; $num_blocks / $sample_size_ops" | bc`
> > +echo "log position = $head1; old log position: $head" >> $seqres.full
> >   echo "blocks_per_op = $blocks_per_op" >>$seqres.full
> > -num_expected_ops=`echo "$log_size_bb / $blocks_per_op" | bc`
> > +
> > +# Since this is a log wrapping test, it's critical to push the log head to
> > +# the point where it will wrap around within twenty rounds of log traffic.
> > +near_end_min=$(echo "$log_size_bb - (10 * $blocks_per_op / 1)" | bc)
Is the 1 doing anything here?  It doesn't look like it really effects 
the result.

> > +echo "near_end_min = $near_end_min" >>$seqres.full
> > +
> > +# Estimate the number of ops needed to get the log head close to but not past
> > +# near_end_min.  We'd rather fall short and have to step our way closer to the
> > +# end than run past the end.
> > +num_expected_ops=$(( 8 * $(echo "$log_size_bb / $blocks_per_op" | bc) / 10))
Also I was trying to figure out what the constants the 8 and 10 come 
from?  Maybe a few extra variables would clarify.  Thanks!

Allison

> >   echo "num_expected_ops = $num_expected_ops" >>$seqres.full
> > +
> >   num_expected_to_go=`echo "$num_expected_ops - $sample_size_ops" | bc`
> >   echo "num_expected_to_go = $num_expected_to_go" >>$seqres.full
> >   
> > @@ -208,13 +230,17 @@ _log_traffic $num_expected_to_go
> >   head=`_log_head`
> >   echo "log position = $head"                     >>$seqres.full
> >   
> > -# e.g. 3891
> > -near_end_min=`echo "0.95 * $log_size_bb" | bc | sed 's/\..*//'`
> > -echo "near_end_min = $near_end_min" >>$seqres.full
> > +# If we fell short of near_end_min, step our way towards it.
> > +while [ $head -lt $near_end_min ]; do
> > +	echo "    bump traffic from $head towards $near_end_min" >> $seqres.full
> > +	_log_traffic 10 > /dev/null 2>&1
> > +	head=$(_log_head)
> > +done
> >   
> >   [ $head -gt $near_end_min -a $head -lt $log_size_bb ] || \
> >       _fail "!!! unexpected near end log position $head"
> >   
> > +# Try to wrap the log, checking for corruption with each advance.
> >   for c in `seq 0 20`
> >   do
> >       echo "   little traffic"            >>$seqres.full
> > diff --git a/tests/xfs/016.out b/tests/xfs/016.out
> > index f7844cdf..f4c8f88d 100644
> > --- a/tests/xfs/016.out
> > +++ b/tests/xfs/016.out
> > @@ -1,4 +1,5 @@
> >   QA output created by 016
> > +*** determine log size
> >   *** reset partition
> >   Wrote 51200.00Kb (value 0xc6)
> >   *** mkfs